A best bet is the DC Comics 2nd Skin Superman Adult Costume (pictured) for $27.25 plus $4.99 for shipping. (Search for "10083644" to find it.) That's the lowest total price we could find by $18. It's available in sizes M or L.
Upgrade to express shipping for an extra $13 and place your order before 3 pm ET on October 28 to guarantee delivery in time for Halloween.